Prepare cupcake batter as directed on box. Divide batter into thirds and color one batter teal, one blue, and one violet. Mix well.

Use a 1 tablespoon portion scoop to scoop 1 scoop of each color batter into cupcake liners. Bake cupcakes as directed on package. Let cool completely.

Divide 1 tub of white frosting into three bowls. Color one bowl teal and one bowl violet. Lay a piece of plastic wrap onto a flat surface. Spread each color next to each other on the plastic wrap, making about a 10-12″ strip. Fold the plastic wrap tightly and twist ends.

Snip the tip of the plastic wrap and place into a plastic piping bag fitted with a star tip. Pipe icing onto cupcakes and top with sprinkles. Add icing decoration.